EP1198491A1

EP1198491A1 - Method for producing polyamides from dinitriles and diamines

Info

Publication number: EP1198491A1
Application number: EP00954469A
Authority: EP
Inventors: Frank Ohlbach; Hermann Luyken
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1999-07-30
Filing date: 2000-07-11
Publication date: 2002-04-24
Anticipated expiration: 2020-07-11
Also published as: ATE251194T1; JP3462868B2; AR024799A1; HUP0202105A2; CA2386888A1; SK1492002A3; PL353271A1; DE50003919D1; BG106341A; DE19935398A1; MXPA02001054A; CZ2002188A3; ES2209950T3; CN1364178A; KR100610728B1; CN1175029C; HUP0202105A3; KR20020016927A; IL147297A0; ZA200201638B

Abstract

A method for producing polyamides from dinitriles and diamines by reacting at least one dinitrile and at least one diamine with water at a temperature of 90-400 DEG C, at a pressure of 0.1 - 50*10<6> Pa and with a mol ratio of water to the sum of dinitrile plus diamine of at least 1:1 in the presence of a heterogeneous catalyst selected from the group consisting of aluminium oxide, zinc oxide, silicon oxide, oxides of the second to seventh subgroup of the periodic table, lanthanoid and actinide oxides, phyllosilicates and zeoliths; The invention also relates to polyamides obtained according to said method.

Description

Besehreibung

Process for the preparation of polyamides from dinitriles and diamines

The present invention relates to a process for the preparation of polyamides from dinitriles and diamines and water at elevated temperature and pressure.

The object of the present invention is to provide a process for the preparation of polyamides from dinitriles and diamines and water which ensures a good space-time yield and simple catalyst removal.

The object is achieved according to the invention by a process for the production of a polyamide by reacting at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C., a pressure of 0.1 to 50 * 10 ⁶ Pa and a molar ratio of water to the sum of dinitrile and diamine of at least 1: 1 in the presence of a heterogeneous catalyst, selected from the group consisting of aluminum oxide, tin oxide, silicon oxide, oxides of the second to sixth subgroup of the periodic table, oxides of lanthanides and actinides, layered silicates, zeolites.

The object is further achieved by a continuous process for the preparation of polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) reaction of at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C. and a pressure of 0.1 to 35 × 10 ⁶ Pa in a flow tube containing a Bronsted acid catalyst selected from a loading contains ta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, whereby an implementation mixture is obtained,

(2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure lower than the pressure in step 1 in the presence of a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the Titanium dioxide can be replaced by tungsten oxide, can be carried out, the temperature and the pressure being selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained, and the first gas phase is separated from the first liquid or the first solid phase or the mixture of first liquid and first solid phase, and

(3) adding a gaseous or liquid phase containing water at a temperature of 150 to 370 ° C, and one of the first liquid or the first solid phase or the mixture of the first liquid and the first solid phase. Pressure from 0.1 to 30 x 10 ⁶ Pa, whereby a product table is obtained.

Furthermore, the object is achieved by a continuous process "for producing a polyaride by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) reaction of at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C. and a pressure of 0.1 to 35 × 10 ⁶ Pa in a flow tube containing a Bronsted acid catalyst selected from a loading Ta-zeolite, layered silicate or a titanium dioxide catalyst from 70 to 100 wt .-% anatase and 0 to 30 wt .-% rutile in the. contains up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, a reaction apparatus being obtained,

(2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure lower than the pressure in step 1 in the presence of a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, the temperature and the pressure are selected so that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained, and the first gas phase of the first liquid or first solid phase or the mixture of first liquid and first solid phase is separated, and (3) adding a gaseous or liquid phase containing water to the first liquid or the first solid phase or the mixture of the first liquid and the first solid phase at a temperature of 150 to 370 ° C. and a pressure of 0.1 to 30 x 10 ⁶ Pa in a flow tube containing a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst made from 70 to 100% by weight of anatase and 0 to 30% by weight of rutile which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, whereby a product mixture is obtained.

The above methods preferably additionally comprise the following stage:

(4) Post-condensation of the product mixture at a temperature of 200 to 350 ° C. and a pressure which is lower than the pressure of stage 3, the temperature and the pressure being chosen so that a second gas phase containing water and ammonia and a second liquid or second solid

Phase or a mixture of second liquid and second solid phase, each containing the polyamide, are obtained.

The object is further achieved by a continuous process for producing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) Implementation of at least one dinitrile and at least one

Diamins with water at a temperature of 90 to 400 ° C and a pressure of 0.1 to 35 x 10 ⁶ Pa in a flow tube, the Brönsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide -Catalyst comprising 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, a reaction mixture being obtained,

(2) further reaction of the reaction mixture at a temperature of 150 to 400 ° C and a pressure lower than the pressure in step 1 in the presence of a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, the temperature and the pressure so-called&- are selected to obtain a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phases, and the first gas phase of the first liquid or first solid phase or the mixture of first liquid and first solid phase is separated, and

(4) post-condensation of the first liquid or the first solid phase or the mixture of the first liquid and first solid phase at a temperature of 200 to 350 ° C. and one

Pressure which is lower than the pressure of stage 3, the temperature and the pressure being chosen such that a second gas phase containing water and ammonia and a second liquid or second solid phase or a mixture of second liquid and second solid phase, each containing the polyamide can be obtained.

The basic procedure of the method according to the invention is described in DE-A-19 804 023, which is older and has no prior publication.

In principle, all dinitriles, i.e. Compounds with at least two nitrile groups are used. Among these, the alpha, omega-dinitriles are preferred, with the latter in particular using alpha, omega-alkylenedinitriles with 3 to 12 carbon atoms, more preferably 3 to 9 carbon atoms in the alkylene radical, or alkylaryldinitriles with 7 to 12 carbon atoms , where preference is given to those which have an alkylene group with at least one carbon atom between the aromatic unit and the two nitrile groups. Among the alkylaryldinitriles, preference is given to those which have the two nitrile groups in the 1,4 position to one another.

The alpha, omega-alkylenedinitriles used are more preferably linear alpha, omega-alkylenedinitriles, the alkylene radical (-CH ₂ -) preferably containing 3 to 11 carbon atoms, more preferably 3 to 9 carbon atoms, such as 1, 3-dicyanopropane, 1, 4-dicyanobutane (adiponitrile, ADN), 1, 5-dicyanopentane, 1, 6-dicyanohexane, 1, 7-dicyano-heptane, 1, 8-dicyanooctane, 1, 9-dicyannonane, particularly preferably Adipodinitrii.

Adiponinitrile can be made according to known. Process obtained by double catalytic addition of HCN to butadiene. Mixtures of several dinitriles or mixtures of a dinitrile with further comonomers, such as dicarboxylic acids, for example adipic acid, can of course also be used.

In principle, all of them can be used as diamines individually or in a mixture

Diamines, i.e. Compounds with at least two amino groups can be used. Of these, the alpha, omega-diamines are preferred, with the latter in particular alpha, o-alka-alkylenediamines having 3 to 14 carbon atoms, more preferably 3 to 10 carbon atoms in the alkylene radical, or alkylaryldiamines having 9 to 14 carbon atoms Atoms are used, with preference being given to those which have an alkylene group with at least one carbon atom between the aromatic unit and the two amino groups. Among the alkylaryldiamines, those which have the two amino groups in the 1,4-position to one another are particularly preferred.

The alpha, omega-alkylenediamines used are more preferably linear alpha, or.ega-alkylenediamines, the alkylene radical (-CH--) preferably containing 3 to 14 carbon atoms, more preferably 3 to 10 carbon atoms, such as 1,3 -Diaminopropane, 1, 4-diaminobutane, 1, 5-diaminopentane, 1, 6-diaminohexane (hexamethylenediamine, HMD), 1, 7-diaminoheptane, 1, 8-diaminooctane, 1, 9-diaminononane, 1, 10-dicyanodecane, particularly preferably hexamethylene diamine.

Hexamethylenediamine can be obtained by processes known per se by double catalytic hydrogenation of the nitrile groups of adiponitrile.

The diamine can advantageously be used dissolved in water.

Mixtures of several diamines or mixtures of a dinitrile with further comonomers can of course also be used.

The molecular ratio of dinitrile to diamine, where, in the following quantities, dinitrile is the sum of dinitrile and any dinitrile equivalents used, that is to say compounds which are to be understood as a dinitrile under the process conditions according to the invention, such as dicarboxylic acids, and diamine is the sum from diamine and any diamine equivalents used, that is to say compounds which react like a diamine under the process conditions according to the invention, should advantageously be between 0.5 to 2, preferably 0.8 to 1.2, in particular 1. In a special embodiment, in particular if one wants to produce copolyamides or branched or chain-extended polyamides, the following mixture is used instead of pure dinitrile and pure diamine:

50 to 99.99, preferably 80 to 90% by weight of dinitrile and diamine in total,

0.01 to 50, preferably from 1 to 30 wt .-% of at least one dicarboxylic acid selected from the group consisting of aliphatic C ₄ -Cιn-α, ω-dicarboxylic acids, aromatic Cβ-Cι ₂ -dicarboxylic acids and Cs-Ca -cycloalkanedicarboxylic,

0 to less than 50, preferably 0 to 30% by weight of an amino nitrile and

0 to 50 preferably 0 to 30% by weight of an α, ω-C ₅ -C ₁₂ amino acid or the corresponding lactam,

0 to 10% by weight of at least one inorganic acid or its salt,

where the sum of the individual weight percentages is 100%.

As dicarboxylic acids, aliphatic C ₄ -C ₁₀ -I, ω-dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, preferably adipic acid and sebacic acid, particularly preferably adipic acid, and aromatic Ca-Cι Use dicarboxylic acids such as terephthalic acid and Cs-Ca cycloalkanedicarboxylic acids such as cyclohexanedicarboxylic acid.

Furthermore, it is also possible to use salts from the dicarboxylic acids and diamines mentioned, in particular the salt from adipic acid and hexamethylenediamine, so-called AH salt.

In principle, all aminonitriles, ie compounds which have both at least one amino group and at least one nitrile group, can in principle be used as the aminonitrile. Among these, $ aminonitriles are preferred, with the latter in particular using $ aminoalkyl nitriles with 4 to 12 carbon atoms, more preferably 4 to 9 carbon atoms in the alkylene radical, or an aminoalkylaryl nitrile with 8 to 13 carbon atoms, where such are preferred which have an alkylene group with at least one carbon atom between the aromatic unit and the amino and nitrile group. Among the aminoalkylaryl nitrites - len are particularly preferred those which have the amino and nitrile groups in the 1,4-position to one another.

Linear ω-aminoalkyl nitriles are more preferably used as the ω-aminoalkyl nitrile, the alkylene radical (-CH--) preferably containing 4 to 12 carbon atoms, more preferably 4 to 9 carbon atoms, such as 6-amino-1- cyanopentane (6-aminocapronitrile), 7-amino-1-cyanohexane, 8-amino-1-cyanoheptane, 9-amino-1-cyanooctane, 10-amino-1-cyanononane, particularly preferably 6-aminocapronitrile.

6-aminocapronitrile is usually obtained by hydrogenating adiponitrile by known processes, for example described in DE-A 836,938, DE-A 848,654 or US Pat. No. 5,151,543.

Mixtures of several aminonitriles or mixtures of an aminonitrile with other comonomers can of course also be used.

If desired, diamines, dinitriles and aminitriles derived from branched alkylene or arylene or alkylarylenes can also be used.

As α, ω-C ₅ -C ₁₂ amino acid, 5-aminopentanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminodode- use canoic acid, preferably 6-aminohexanoic acid.

The process according to the invention is carried out at temperatures from 90 to 400 ° C., advantageously 150 to 350 ° C., at pressures of 0.1 to 50 * 10 ⁶ Pa.

Oxides selected from the group consisting of aluminum oxide, tin oxide, silicon oxide as pyrogenically produced silicon oxide, as silica gel, diatomaceous earth, quartz, sheet silicate or mixtures thereof, as well as oxides of the metals of the second to sixth subgroup of the periodic table, such as titanium dioxide, amorphous, can be used as heterogeneous catalysts. as anatase or rutile, zirconium oxide, zinc oxide, oxides of lanthanides and actinides, such as cerium oxide, thorium oxide, praseodymium oxide, samarium oxide, rare earth mixed oxides or mixtures of the aforementioned oxides.

Other catalysts can be, for example:

Vanadium oxide, niobium oxide, iron oxide, chromium oxide, molybdenum oxide, tungsten oxide or mixtures thereof. Mixtures of the oxides mentioned are also possible. Some sulfides, selenides and tellurides such as zinc telluride, tin seienide, molybdenum sulfide, tungsten sulfide, sulfides of nickel, zinc and chromium can be used.

The abovementioned compounds can be doped with compounds of the 1st and 7th main groups of the periodic table or contain them.

Furthermore, zeolites, such as beta-zeolites, phosphates, and hetero polyacids, and also acidic and alkaline ion exchangers, such as examples of play Naphion ^® as suitable catalysts.

If necessary, these catalysts can be up to

50% by weight of copper, tin, zinc, manganese, iron, cobalt, nickel,

Contain ruthenium, palladium, platinum, silver or rhodium.

Catalysts are preferably selected from the group consisting of beta zeolite, layered silicate and in particular titanium dioxide, the titanium dioxide advantageously consisting of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the Titanium dioxide can be replaced by tungsten oxide, or mixtures thereof. Such catalysts are particularly preferred if they can act as Bronsted acid.

Depending on the composition of the catalyst, the catalysts can be used as full contacts or supported catalysts. For example, titanium dioxide can be used as a strand of titanium dioxide or as a layer of titanium dioxide applied to a carrier. All methods described in the literature can be used to apply titanium dioxide to a support such as silicon dioxide, aluminum oxide or zirconium dioxide. For example, a thin layer of titanium dioxide can be applied by hydrolysis of Ti-organyls such as Ti-isopropylate or Ti-butoxide, or by hydrolysis of TiCl ₄ or other inorganic compounds containing Ti. Brine containing titanium dioxide can also be used.

Other suitable compounds are zirconyl chloride, aluminum nitrate and cerium nitrate.

Suitable carriers are powders, extrudates or tablets of the oxides mentioned themselves or other stable oxides such as silicon dioxide. The carriers used can be designed to be macroporous in order to improve the mass transport.

The method according to the invention can be carried out continuously or discontinuously. According to the invention, water is used in a molar ratio of the sum of dinitrile and diamine to water of at least 1: 1, advantageously in the range from 1: 1 to 1:10, particularly preferably from 1: 2 to 1: 8, very particularly preferably from 1 : 2 to 1: 6, a, the use of water in excess, based on the sum of dinitrile and diamine is preferred.

In a first stage (stage 1) it is advantageous to use at least one dinitrile and at least one diamine with water, at a temperature of approximately 90 to approximately 400 ° C., preferably approximately 180 to approximately 310 ° C. and in particular approximately 220 to approximately 270 ° C. heated, wherein a pressure of about 0.1 to about 15 x 10 ⁶ Pa, preferably about 1 to about 10 x 10 ⁶ Pa and in particular about 4 to about 9 x 10 ⁶ Pa is set. In this stage, pressure and temperature can be coordinated with one another in such a way that a liquid or a solid phase and a mixture of liquid or solid phase and a gaseous phase are obtained.

In this embodiment, the liquid or solid phase or the mixture of liquid and solid phase corresponds to the reaction mixture, while the gaseous phase is separated off. In this step, the gaseous phase can be immediately separated from the liquid or solid phase or the mixture of solid or liquid phase, or the reaction mixture formed within this step can be biphasic liquid-gaseous, solid-gaseous or liquid / solid-gaseous available. Of course, the pressure and temperature can also be coordinated with one another in such a way that the reaction mixture is single-phase, solid or liquid.

The gas phase can be separated by using stirred or non-stirred separating kettles or boiler cascades and by using evaporator apparatuses, e.g. by circulation evaporators or thin film evaporators, e.g. by film extruders or by ring disk reactors, which guarantee an enlarged phase interface. Pumping around the reaction mixture or using a loop reactor may be necessary in order to enlarge the phase interface. Furthermore, the separation of the gas phase can be promoted by adding water vapor or inert gas to the liquid phase.

The pressure is preferably set at a preselected temperature such that it is lower than the equilibrium vapor pressure of ammonia, but greater than the equilibrium vapor pressure of the other components in the reaction mixture at the predetermined temperature. In this way, the separation of Ammonia favors and thus the hydrolysis of the acid amide groups can be accelerated.

In the two-phase procedure, a pressure is preferably selected which is greater than the vapor pressure of pure water belonging to the melt temperature of the reaction mixture, but less than the equilibrium vapor pressure of ammonia.

In a particularly preferred embodiment of the two-phase mode of operation, a vertical flow tube is used which is flowed through from bottom to top and, if desired, has a further opening for gas phase separation above the product outlet. This tubular reactor can be completely or partially filled with catalyst granules. In a preferred embodiment, the vertical reactor is filled to a maximum of up to the phase boundary with catalyst material in a two-phase procedure.

In another, particularly preferred embodiment of the first stage, the pressure is selected so that the reaction mixture is in one phase liquid, i.e. there is no gas phase in the reactor. In this single-phase mode of operation, the preferred embodiment is a flow tube filled exclusively with catalyst material.

The dinitrile / diamine / water mixture can advantageously be heated using a heat exchanger before being introduced into the first stage. Of course, dinitrile, diamine and the water can also be heated separately and mixed in the first stage by using mixing elements.

Concerning. there are no restrictions on the residence time of the reaction mixture in the first stage; however, it is generally selected to range from about 10 minutes to about 10 hours, preferably from about 30 minutes to about 6 hours.

Although there are also no restrictions with regard to the conversion of nitrile groups in stage 1, the conversion of nitrile groups in stage 1 is generally not less than approximately 70 mol%, preferably at least approximately 95 mol% and in particular approximately, in particular for economic reasons 97 to about 99 mol%, based in each case on the mol number of dinitrile and diamine used. The conversion of nitrile groups is usually determined by means of IR spectroscopy (CN valence oscillation at 2247 wave numbers), NMR or HPLC, preferably by means of IR spectroscopy.

Furthermore, it is not excluded according to the invention that the reaction in stage 1 also in the presence of oxygen-containing phosphorus compounds, in particular phosphoric acid, phosphorous acid and hypophosphorous acid and their alkali metal and alkaline earth metal salts and ammonium salts such as Na ₃ PO ₄ , aH ₂ PO ₄ , Na ₂ HP0 ₄ , NaH ₂ P0 ₃ , Na ₂ HP0 ₃ , NaH ₂ P0 ₂ , K ₃ P0 ₄ , KH ₂ P0 ₄ , K ₂ HP0 ₄ , KH ₂ P0 ₃ , K ₂ HP0 ₃ , KHP0, whereby the molar ratio of Sum of dinitrile and diamine to phosphorus compounds in the range from 0.01: 1 to 1: 1, preferably from 0.01: 1 to 0.1: 1.

The reaction is carried out in stage 1 in a flow tube which contains a Bronsted acid catalyst selected from a beta zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0-30% by weight of rutile , in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide. If very pure dinitrile and very pure diamine are used, the proportion of anatase in the titanium dioxide catalyst should be as high as possible. A pure anatase catalyst is preferably used. If the dinitrile or the diamine used contains impurities, for example 1 to 3% by weight of impurities, a titanium dioxide catalyst which contains a mixture of anatase and rutile is preferably used. The proportion of anatase is preferably 70 to 80% by weight and the proportion of rutile is 20 to 30% by weight. In this case, a titanium dioxide catalyst composed of approximately 70% by weight of anatase and approximately 30% by weight of rutile is particularly preferably used. The catalyst preferably has a pore volume of 0.1 to 5 ml / g, particularly preferably 0.2 to 0.5 ml / g. The average pore diameter is preferably 0.005 to 0.1 μm, particularly preferably 0.01 to 0.06 μm. When working with highly viscous products, the medium pore diameter should be large. The cutting hardness is preferably greater than 20 N, particularly preferably> 25 N. The BET surface area is preferably more than 40 m ² / g, particularly preferably more than 100 m / g. If the BET surface area is smaller, the bulk volume should be chosen accordingly in order to ensure sufficient catalyst activity. Particularly preferred catalysts have the following properties: 100% anatase; 0.3 ml / g pore volume; 0.02 µm mean pore diameter; 32 N cutting hardness; 116 m / g BET surface area or 84% by weight anatase; 16 wt% rutile; 0.3 ml / g pore volume; 0.03 μm average pore diameter; 26 N cutting hardness; 46 m ² / g BET surface area. The catalysts can be made from commercially available powders such as those from Degussa, Finti or Kemira are offered to be manufactured. When a proportion of tungsten oxide is used, up to 40% by weight, preferably up to 30% by weight, particularly preferably 15 to 25% by weight, of the titanium dioxide are replaced by tungsten oxide. The catalysts can be assembled as described in Ertl, Knözinger, Weitkamp: "Handbook of heterogeneous catalysis", VCH Weinheim, 1997, pages 98ff. The catalyst can be used in any suitable form. It is preferably used in the form of moldings, strands or granules, in particular granules. The granulate is preferably so large that it can be easily separated from the product mixture and does not impair the flowability of the product during the reaction.

The granular form of the catalyst makes it possible to mechanically separate it at the discharge from the first stage. For example, mechanical filters or screens are provided on the discharge of the first stage. If the catalyst is also used in the second and / or third stage, it is preferably in the same form.

According to the invention, the reaction mixture obtained in the first stage is heated in stage 2 at a temperature of about 200 (150) to about 350 (400) ° C, preferably a temperature in the range of about 210 (200) to about 330 (330) ° C and especially in the range of about 230 (230) to about 270

(290) ° C and a pressure that is lower than the pressure in stage 1 further implemented. Preferably, the pressure in the second stage is at least about 0.5 x 10 ⁶ Pa lower than the pressure in stage 1, with the pressure generally in the range from about 0.1 to about 45 x 10 ⁶ Pa, preferably about 0.5 up to about 15 x 10 ⁶ Pa and in particular about 2 to about 6 x 10 ⁶ Pa (values in brackets: without catalyst).

In step 2, the temperature and the pressure are selected so that a first gas phase and a first liquid or first solid phase or a mixture of first liquid and first solid phase are obtained, and the first gas phase from the first liquid or first solid phase or the mixture of first liquid and first solid phase is separated off.

The first gaseous phase, which consists essentially of ammonia and water vapor, is generally removed continuously using a distillation device, such as a distillation column. The organic constituents of the distillate, which may have been separated during this distillation, to a large extent unreacted dinitrile and diamine can be completely or partially recycled in stage 1 and / or stage 2.

The residence time of the reaction mixture in stage 2 is not subject to any restrictions, but is generally from about 10 minutes to about 5 hours, preferably from about 30 minutes to about 3 hours.

The product line between the first and second stages may contain packing elements, such as Raschig rings or Sulzer mixing elements, which allow the reaction mixture to relax in a controlled manner in the gas phase. This applies in particular to single-phase operation.

The reactor of the second stage preferably also contains the catalyst material according to the invention, in particular in granular form. It has been found that the reactor has a further improvement in the product properties compared to a catalyst-free reactor, in particular at higher pressures and / or with a large excess of water in the reaction mixture allows. Temperature and pressure should be chosen so that the viscosity of the reaction mixture remains small enough to avoid clogging of the catalyst surface. According to the invention, screens or filters which guarantee the purity of the reaction mixture and separate the catalyst from the reaction mixture are also used on the discharge from the second process stage.

In stage 3, the first liquid or the first solid phase or the mixture of the first liquid and the first solid phase is mixed with a gaseous or liquid phase which contains water, preferably water or water vapor. This happens continuously. The amount of water added (as a liquid) is preferably in the range from approximately 50 to approximately 1500 ml, more preferably approximately 100 to approximately 500 ml, in each case based on 1 kg of the first liquid or first solid phase or the mixture of first liquid and first solid phase. This addition of water primarily compensates for the water losses caused in stage 2 and promotes the hydrolysis of acid amide groups in the reaction mixture. This results in a further advantage of this invention that the mixture of

Starting products, as used in stage 1, can only be used with a small excess of water.

The water-containing gaseous or liquid phase is preferably preheated in a heat exchanger before being introduced in stage 3 and then with the first liquid or the first solid phase or the mixture of first solid and first liquid phase mixed. If necessary, mixing elements can be used in the reactor to promote the mixing of the components. Stage 3 can be operated at a temperature of 150 to 37 ° C and a pressure of 0.1 to 30 x 10 ⁶ Pa. If a catalyst bed according to the invention is present, the conditions applicable to stage 1 can be applied. Otherwise, the temperature is preferably 180 to 300 ° C, particularly preferably 220 to 280 ° C. The pressure is preferably 1 to 10 x 10 ⁶ Pa, particularly preferably 2 x 10 ⁶ to 7 x 10 ⁶ Pa.

The pressure and temperature can be matched to one another in such a way that the reaction mixture is single-phase liquid or single-phase solid. In another embodiment, pressure and temperature are selected so that a liquid or a solid phase or a mixture of solid and liquid phase and a gaseous phase are obtained. In this embodiment, the liquid or solid phase or the mixture of liquid and solid phase corresponds to the product mixture, while the gaseous phase is separated off. In the course of this stage, the gaseous phase can be immediately separated from the liquid or solid phase or the mixture of solid or liquid phase, or the reaction mixture which forms within this stage can be in two phases, liquid-gaseous, solid-gaseous or liquid / solid-gaseous ,

At a preselected temperature, the pressure can be set so that it is less than the equilibrium vapor pressure of ammonia, but greater than the equilibrium vapor pressure of the other components in the reaction mixture at the given one

Temperature. In this way, the pre-ammonia deposition can be favored and the hydrolysis of the acid amide groups can be accelerated.

The apparatus / reactors that can be used in this stage can be identical to those in stage 1, as discussed above.

The residence time at this stage is also not restricted, but for economic reasons it is generally chosen in the range between about 10 minutes to about 10 hours, preferably between about 60 to about 8 hours, particularly preferably about 60 minutes to about 6 hours.

The product mixture obtained in stage 3 can then be further processed as described below. In a preferred embodiment, the product mixture of stage 3 is subjected to a post-condensation in a fourth stage at a temperature of approximately 200 to approximately 350 ° C., preferably a temperature of approximately 220 to 300 ° C. and in particular approximately 5 240 to 270 ° C. Step 4 is carried out at a pressure which is below the pressure of step 3, and preferably in a range from approximately 5 to 1000 × 10 ³ Pa, more preferably approximately 10 to approximately 300 × 10 ³ Pa. In this step, temperature and pressure are selected so that a second gas phase and a second liquid or solid phase or a mixture of second liquid and second solid phases which contain the polyamide are obtained.

The post-condensation according to stage 4 is preferably carried out such that the relative viscosity (measured at a temperature of 25 ° C. and a concentration of 1 g polymer per 100 ml in 96% by weight sulfuric acid) of the polyamide has a value in Ranges from about 1.6 to about 3.5. In a preferred embodiment, any water that may be present can be driven out of the liquid phase by means of an inert gas such as nitrogen.

The residence time of the reaction mixture in stage 4 depends in particular on the desired relative viscosity, the

Temperature, pressure and the amount of water added in stage 3.

If stage 3 is operated as a single phase, fillers, existing e.g. from Raschig rings or Sulzer mixing elements can be used, which allow a controlled relaxation of the reaction mixture in the gas phase.

The fourth stage can also be operated with the catalyst according to the invention. It was found that the use of the catalyst in process stage 4 improves the molecular weight build-up in particular if the relative viscosity of the discharge from the third or - in the case of the three-stage procedure - second stage is less than RV = 1.6 - and / or the molar nitrile group and acid amide content in the polymer is greater than 1%, in each case based on the sum of the number of moles of dinitrile and diamine used.

In a further embodiment, step 3 can be dispensed with according to the invention and steps (1), (2) and (4) are carried out to produce the polyamide. This variant is preferably carried out as follows:

Stage 1 is implemented as described above. The reaction mixture is treated in stage 2 as described above or at a temperature in the range from about 220 to about 300 ° C. and a pressure in the range from about 1 to about 7 × 10 ^δ Pa, the pressure in the second stage being at least 0. 5 x 10 ⁶ Pa is lower than in stage 1. At the same time, the resulting first gas phase is separated from the first liquid phase.

The first liquid phase obtained in stage 2 is treated in stage 4 as in stage 1 or at a temperature in the range from about 220 to 300 ° C. and a pressure in the range from about 10 to about 300 × 10 ³ Pa, the resultant second gas phase containing water and ammonia is separated from the second liquid phase. Within this step, the relative viscosity (measured as defined above) of the polyamide obtained is adjusted to a desired value in the range from approximately 1.6 to approximately 3.5 by selection of the temperature and the residence time.

The second liquid phase thus obtained is then discharged by customary methods and, if desired, worked up.

In a further preferred embodiment of the present invention, at least one of the gas phases obtained in the respective stages can be returned to at least one of the preceding stages.

It is further preferred that in stage 1 or in stage 3 or both in stage 1 and in stage 3 the temperature and the pressure are chosen such that a liquid or a solid phase or a mixture of liquid and solid phase and a gas-free - Mige phase are obtained, and the gaseous phase is separated.

In the drawing, an apparatus for carrying out the method according to the invention is shown in FIG.

Here mean:

V: Submission

ADN: adiponitrile HMD: hexamethylene diamine

1: Level 1

2: Level 2 3: level 3

4: level 4

A: From order

Furthermore, chain extension or branching or a combination of both can also be carried out in the context of the method according to the invention. For this purpose, substances known to the person skilled in the art are added in the individual stages for branching or extending the polymers. These substances are preferably added in stage 3 or 4.

The following substances can be mentioned:

Trifunctional Arr.ine or carboxylic acids as branching agents or crosslinkers. Examples of suitable at least trifunctional amines or carboxylic acids are described in EP-A-0 345 648. The at least trifunctional amines have at least three amino groups which are capable of reacting with carboxylic acid groups. They preferably have no carboxylic acid groups. The at least trifunctional carboxylic acids have at least three carboxylic acid groups capable of reacting with amines, which can also be present, for example, in the form of their derivatives, such as esters. The carboxylic acids preferably have no amino groups capable of reacting with carboxylic acid groups. Examples of suitable carboxylic acids are trimesic acid, trimerized fatty acids, which can be produced, for example, from oleic acid and can have 50 to 60 carbon atoms, naphthalene polycarboxylic acids, such as naphthalene !, 3, 5, 7-tetracarboxylic acid. The carboxylic acids are preferably defined organic compounds and not polymeric compounds.

Amines with at least 3 amino groups are, for example, nitrilotestylkylamine, in particular nitrilotriethanamine, dialkylenetriamines, in particular diethylenetriamine, trialkylenetetramine and tetraalkylenepentamine, the alkylene radicals preferably being ethylene radicals. Dendrimers can also be used as amines. The dendrimers preferably have the general formula I.

(R ₂ N- ⁽ CK ₂ ⁾ n ⁾ 2N- ⁽ CH ₂ ⁾ _x -N ⁽⁽ CH ₂ ⁾ n-NR ₂ ) 2 (I)

in the

RH or - (CH) _n -NR ^: ₂ with

R ¹ H or - (CH ₂ ) _n -NR ^:: ₂ with R ² H or - (CH ₂ ) _n -NR ³ ₂ with

R ^{3 is} E or - (CH ₂ ) _n -NH ₂ ,

n has an integer value from 2 to 6 and

x has an integer value from 2 to 14.

N preferably has an integer value of 3 or 4, in particular 3 and x has an integer value of 2 to 6, preferably 2 to 4, in particular 2. The radicals R can also have the meanings indicated independently of one another. The radical R is preferably a hydrogen atom or a radical - (CH ₂ ) -NE ₂ .

Suitable carboxylic acids are those with 3 to 10 carboxylic acid groups, preferably 3 or 4 carboxylic acid groups. Preferred carboxylic acids are those with aromatic and / or heterocyclic nuclei. Examples are benzyl, naphthyl, anthracene, biphenyl, triphenyl or heterocycles such as pyridine,

Bipyridine, pyrrole, indole, furan, thiophene, purine, quinoline, phenanthrene, porphyrin, phthalocyanine, naphthalocyanine. Preferred are 3,5,3 ', 5' -biphenyltetracarboxylic acid phthalocyanine, naphthalocyanine, 3, 5, 5 ', 5' -biphenyltetracarboxylic acid, 1,3,5,7-naphthalene tetracarboxylic acid, 2, 4, 6-pyridine tricarboxylic acid, 3, 5, 3 '5' bipyridyl tetracarboxylic acid, 3, 5, 3 '5' benzophenonetetracarboxylic acid, 1, 3, 6, 8-acridine tetracarboxylic acid, particularly preferably 1, 3, 5-3-benzene tricarboxylic acid (trimesic acid) and 1, 2 , 4, 5-benzene-tetracarboxylic acid. Such compounds are obtained technically - lent or can according to that described in DΞ-A-43 12 182. Process are made. When using ortho-substituted aromatic compounds, imide formation is preferably prevented by selecting suitable reaction temperatures.

These substances are at least trifunctional, preferably at least tetrafunctional. The number of functional groups can be 3 to 16, preferably 4 to 10, particularly preferably 4 to 8. Either at least trifunctional amines or at least trifunctional carboxylic acids are used in the processes according to the invention, but no mixtures of corresponding amines or carboxylic acids. However, small amounts of at least trifunctional amines can be contained in the trifunctional carboxylic acids and vice versa. The substances are present in the amount of 1 to 50 µmol / g polyamide, preferably 1 to 35, particularly preferably 1 to 20 µmol / g polyamide. The substances are preferably present in an amount of 3 to 150, particularly preferably 5 to 100, in particular 10 to 70 μmol / g of polyamide in equivalents. The equivalents relate to the number of functional amino groups or carboxylic acid groups.

Difunctional carboxylic acids or difunctional amines serve as chain extenders. They have 2 carboxylic acid groups that can be reacted with amino groups or 2 amino groups that can be reacted with carboxylic acids. The difunctional carboxylic acids or amines contain, apart from the carboxylic acid groups or arrino groups, no further functional groups which can react with amino groups or carboxylic acid groups. They preferably do not contain any further functional groups. Examples of suitable difunctional amines are those which form salts with difunctional carboxylic acids. They can be linearly aliphatic, such as C 1 ₄ -alkylenediamine, preferably C ₆ -alkylene diamine, for example hexylenediamine. They can also be cycloaliphatic. Examples are isophoronediamine, dicycycan, laromine. Branched aliphatic diamines can also be used, for example Vestamin TMD (trimethylhexamethylene diamine, manufactured by Huls AG). The entire amines can each be substituted by Cι_ι ₂ - preferably Cι-14 alkyl radicals on the carbon skeleton.

Difunctional carboxylic acids are, for example, those which form salts with difunctional diamines. They can be linear aliphatic dicarboxylic acids, which preferably are C ₄ _ acids ₂₀ -Dicarbon-. Examples are adipic acid, azelaic acid, sebacic acid, suberic acid. They can also be aromatic. Examples are isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, as well as dimerized fatty acids.

The difunctional basic building blocks (c) are preferably used in amounts of 1 to 55, particularly preferably 1 to 30, in particular i to 15 μm / g polyamide.

The product mixture obtained in stage 3 or the second liquid or second solid phase or the mixture of second liquid and second solid phase (from stage 4) which contains the polyamide, preferably a polymer melt, is advantageously carried by conventional methods, for example using a Pump out of the reaction vessel. The polyamide obtained can then be prepared by methods known per se, as described, for example, in DE-A 43 21 683 (p. 3, line 54 to p. 4, line 3) are described in detail.

In a preferred embodiment, the cyclic dimer content in the polyamide-6 obtained according to the invention can be reduced further by first extracting the polyamide with an aqueous solution of caprolactam and then with water and / or the gas phase extraction (described for example in the EP A-0 284 968). The low-molecular constituents obtained in this aftertreatment, such as caprolactam and its linear and cyclic oligomers, can be returned to the first and / or second and / or third stage.

The starting mixture and the reaction mixture can in all. Step chain regulators, such as aliphatic and aromatic carboxylic and dicarboxylic acids, and catalysts, such as oxygen-containing phosphorus compounds, in amounts in the range from 0.01 to 5% by weight, preferably from 0.2 to 3% by weight, based on the amount of polyamide-forming monomers and amino nitriles used are added. Suitable chain regulators are, for example, propionic acid, acetic acid, benzoic acid, terephthalic acid and triacetone diamine.

Additives and fillers such as pigments, dyes and stabilizers are generally added to the reaction mixture before granulation, preferably in the second, third and fourth stages. Fillers and additives are particularly preferred when the reaction or polymer mixture is no longer reacted in the presence of fixed bed catalysts in the further course of the process. The compositions can contain from 0 to 40% by weight, preferably from 1 to 30% by weight, based on the overall composition, of one or more impact-modifying rubbers as additives.

For example, Usual impact modifiers are used, which are suitable for polyamides and / or polyarylene ethers.

Rubbers that increase the toughness of polyamides generally have two essential characteristics: they contain an elastomer. Portions that have a glass transition temperature of less than -10 ° C, preferably less than -30 ° C, and they contain at least one functional group that can interact with the polyamide. Suitable functional groups are, for example, carboxylic acid, carboxylic anhydride, carboxylic ester, carboxamide, carboximide, amino, hydroxyl, epoxy, urethane and oxazoline groups. The following are examples of rubbers which increase the toughness of the blends:

EP or EPDM rubbers that have been grafted with the above functional groups. Suitable grafting reagents are, for example, maleic anhydride, itaconic acid, acrylic acid, glycidyl acrylate and glycidyl methacrylate.

These monomers can be grafted onto the polymer in the melt or in solution, if appropriate in the presence of a radical start such as cumene hydroperoxide.

The copolymers of α-olefins described under the polymers A, including in particular the ethylene copolymers, can also be used as rubbers instead of polymers A and added to the compositions according to the invention as such.

Core-shell graft rubbers are another group of suitable elastomers. These are graft rubbers produced in emulsion, which consist of at least one hard and one soft component. A hard component usually means a polymer with a glass transition temperature of at least 25 ° C, a soft component a polymer with a glass transition temperature of at most 0 ° C. These products have a structure consisting of a core and at least one shell, the structure resulting from the order in which the monomers are added. The soft constituents are generally derived from butadiene, isoprene, alkyl acrylates, alkyl methacrylates or siloxanes and optionally other comonomers. from. Suitable siloxane cores can be prepared, for example, from cyclic oligomeric octamethyltetrasiloxane or tetravinyltetramethyltetrasiloxane. These can be reacted, for example, with γ-mercaptopropylmethyldimethoxysilane in a ring-opening cationic polymerization, preferably in the presence of sulfonic acids, to give the soft siloxane cores. The siloxanes can also be crosslinked by, for example, carrying out the polymerization reaction in the presence of silanes with hydrolyzable groups such as halogen or alkoxy groups such as tetraethoxysilane, methyltrimethoxysilane or phenyltrimethoxysilane. Examples of suitable comonomers here are styrene, acrylonitrile and crosslinking or graft-active monomers with more than one polymerizable double bond, such as diallyl phthalate, divinylbenzene, butanediol diacrylate or triallyl (iso) cyanurate. The hard constituents are generally derived from styrene, α-methylstyrene and their copolymers, here acrylonitrile, methacrylonitrile and methyl methacrylate are to be listed as comonomers.

Preferred core-shell graft rubbers contain a soft core and a hard shell or a hard core, a first soft shell and at least one further hard shell. Functional groups such as carbonyl, carboxylic acid, acid anhydride, acid amide, acid imide, carboxylic ester, amino, hydroxyl, epoxy, oxazoline, urethane, urea, lactam or halobenzyl groups are incorporated here preferably by adding suitably functionalized monomers in the polymerization of the last shell. Suitable functionalized monomers are, for example, maleic acid, maleic anhydride, mono- or diester or maleic acid, tert-butyl (meth) acrylate, acrylic acid, glycidyl (meth) acrylate and vinyloxazoline. The proportion of monomers with functional groups is in general. 0.1 to 25 wt .-%, preferably 0.25 to 15 wt .-%, based on the total weight of the core-shell graft rubber. The weight ratio of soft to hard components is generally 1: 9 to 9: 1, preferably 3: 7 to 8: 2.

Rubbers of this type which increase the toughness of polyamides are known per se and are described, for example, in ΞP-A-0 208 187.

Another group of suitable impact modifiers are thermoplastic polyester elastomers. Polyester elastomers are understood to mean segmented copolyether esters which contain long-chain segments which are generally derived from poly (alkylene) ether glycols and short-chain segments which are derived from low-molecular weight dioien and dicarboxylic acids. Such products are known per se and are known in the literature, e.g. in US 3,651,014. Corresponding products are also commercially available under the names Hytrel® (Du Pont), Arnitel® (Akzo) and Pelprene® (Toyobo Co. Ltd.).

Mixtures of different rubbers can of course also be used.

Further additives include processing aids, stabilizers and oxidation retardants, agents against heat decomposition and decomposition by ultraviolet light, lubricants and mold release agents, flame retardants, dyes and pigments and plasticizers. Their proportion is generally up to 40, preferably up to 15% by weight. on the total weight of the composition. Pigments and dyes are generally present in amounts of up to 4, preferably 0.5 to 3.5 and in particular 0.5 to 3% by weight.

The pigments for coloring thermoplastics are generally known, see e.g. R. Gächter and H. Müller, paperback of the

Plastic additives, Carl Hanser Verlag, 1983, pages 494 to 510. The first preferred group of pigments are white pigments such as zinc oxide, zinc sulfide, lead white (2 PbC0 ₃ Pb (OH) ₂ ), lithopone, antimony white and titanium dioxide. Of the two most common crystal modifications (rutile and anatase type) of titanium dioxide, the rutile form is used in particular for the white coloring of the molding compositions according to the invention.

Black color pigments which can be used according to the invention are iron oxide black (Fe ₃ 0), spinel black (Cu (Cr, Fe) ₂ O ₄ ), manganese black (mixture of manganese dioxide, silicon dioxide and iron oxide), cobalt black and antimony black and particularly preferably carbon black , which is mostly used in the form of furnace black or gas black (see G. Benzing, Pigments for Paints, Exert-Verlag (1988), p. 78ff).

Of course, inorganic colored pigments such as chrome oxide green or organic colored pigments such as azo pigments and phthalocyanines can be used according to the invention to adjust certain color shades. Pigments of this type are generally commercially available.

It may also be advantageous to use the pigments or dyes mentioned in a mixture, e.g. Carbon black with copper phthalocyanines, since it is generally easier to disperse colors in thermoplastics.

Oxidation retarders and heat stabilizers which can be added to the thermoplastic compositions according to the invention are e.g. Group I metals of the Periodic Table, e.g. Sodium, potassium, lithium halides, optionally in combination with copper (I) halides, e.g. Chlorides, bromides or iodides. The halides, especially of copper, can also contain electron-rich p-ligands. An example of such copper complexes are Cu halide complexes with e.g.

Called triphenylphosphine. Zinc fluoride and zinc chloride can also be used. Furthermore, sterically hindered phenols, hydroquinones, substituted representatives of this group, secondary aromatic amines, optionally in combination with phosphorus-containing acids or their salts, and mixtures thereof Compounds, preferably in a concentration of up to 1% by weight, based on the weight of the mixture, can be used.

Examples of UV stabilizers are various substituted resorcinols, salicylates, benzotriazoles and benzophenones, which are generally used in amounts of up to 2% by weight.

Lubricants and mold release agents, which are usually added in amounts of up to 1% by weight to the thermoplastic composition, are stearic acid, stearyl alcohol, alkyl stearate esters and amides and esters of pentaerythritol with long-chain fatty acids. Salts of calcium, zinc or aluminum of stearic acid and dialkyl ketones, e.g. Distearyl ketone can be used.

The present invention further relates to a polyamide which can be produced by one of the processes.

Claims

claims

1. Process for the production of a polyamide by reacting at least one dinitrile and at least one diamine with

Water at a temperature of 90 to 400 ° C, a pressure of 0.1 to 50 * 10 ⁶ Pa and a molar ratio of water to the sum of dinitrile and diamine of at least 1: 1 in the presence of a heterogeneous catalyst selected from the group consisting of aluminum oxide, tin oxide, silicon oxide, oxides of the second to sixth subgroup of the periodic table, oxides of lanthanides and actinides, layered silicates, zeolites.

2. The method according to claim 1, wherein a catalyst selected from the group consisting of beta zeolite, layered silicate and titanium dioxide is used.

3. The method according to claim 1 or 2, wherein as a catalyst titanium dioxide, the titanium dioxide advantageously from 70 to 100 wt .-% anatase and 0 to 30 wt .-% rutile, in which up to 40 wt .-% of the titanium dioxide by tungsten oxide can be replaced.

4. The method according to claims 1 to 3, wherein in the titanium oxide up to 40% by weight of the titanium oxide is replaced by tungsten oxide.

5. The method according to claims 1 to 4, wherein the process is carried out continuously.

6. The method according to claim 1 to 4, wherein the process is carried out batchwise.

7. A continuous process for producing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) Reaction of at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C and a pressure of 0.1 to 35 x 10 ⁶ Pa in one

Flow tube containing a Brönsted acid catalyst selected from a beta zeolite, layered silicate or a titanium dioxide catalyst comprising 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight % of the titanium dioxide can be replaced by tungsten oxide, whereby a reaction mixture is obtained. (2) Further reaction of the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the pressure in stage 1, in the presence of a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, the temperature and the pressure are selected so that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained, and the first gas phase of the first liquid or first solid phase or the mixture of first liquid and first solid phase is separated, and

(3) adding a gaseous or liquid phase containing water to the first liquid or the first solid phase or the mixture of the first liquid and the first solid phase at a temperature of 150 to

370 ° C and a pressure of 0.1 to 30 x 10 ⁶ Pa, whereby a product mixture is obtained.

8. A continuous process for producing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) reaction of at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C. and a pressure of 0.1 to 35 × 10 ⁶ Pa in a flow tube containing a Bronsted acid catalyst selected from a beta Zeolite, layered silicate or a titanium dioxide catalyst comprising 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, whereby an implementation mixture is obtained,

(2) further reaction of the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the pressure in stage 1, which in the presence of a Bronsted acid catalyst selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst composed of 70 to 100% by weight of anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, the temperature and the Pressure be chosen so that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained, and the first gas phase is separated from the first liquid or first solid phase or the mixture of first liquid and first solid phase, and

370 ° C and a pressure of 0.1 to 30 x 10 ⁶ Pa in a flow tube, the Brönsted acid catalyst, selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst from 70 to 100 wt .-% anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, to give a product mixture.

9. The method according to claim 7 or 8, which additionally comprises the following step:

(4) post-condensation of the product mixture at a temperature of 200 to 350 ° C and a pressure which is lower than the pressure of stage 3, the temperature and the pressure being chosen so that a second gas phase containing water and ammonia and a second liquid or second solid phase or a mixture of second liquid and second solid phase, each containing the polyamide, are obtained.

10. A continuous process for producing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises the following steps:

(1) reaction of at least one dinitrile and at least one diamine with water at a temperature of 90 to 400 ° C. and a pressure of 0.1 to 35 × 10 ⁶ Pa in a flow tube containing a Bronsted acid catalyst selected from a beta Zeolite, layered silicate or a titanium dioxide catalyst from 70 to 100 wt .-%

Contains anatase and 0 to 30% by weight of rutile, in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, a reaction mixture being obtained,

(2) further implementation of the implementation mix at a

Temperature of 150 to 400 ° C and a pressure which is lower than the pressure in stage 1, which in the presence of a Brönsted acid catalyst, selected from a beta-zeolite, layered silicate or a titanium dioxide catalyst of 70 to 100 wt .-% anatase and 0 to 30 wt .-% rutile, in which up to 40 wt .-% of the titanium dioxide 5 tungsten oxide can be replaced, can be carried out, the temperature and the pressure being selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained, and the first 10 Gas phase is separated from the first liquid or the first solid phase or the mixture of first liquid and first solid phase, and

(4) post-condensation of the first liquid phase or the first 15 solid phase or the mixture of the first liquid phase and the first solid phase at a temperature of 200 to 350 ° C. and a pressure which is lower than the pressure of stage 3, the temperature and the pressure is selected so that a second gas phase containing water and ammonia and a second liquid or second solid phase or a mixture of second liquid and second solid phase, each containing the polyamide, are obtained.

11. The method according to any one of claims 7 to 10, wherein in stage 1 or in stage 3 or both in stage 1 and in stage 3, the temperature and the pressure are selected so that a liquid or a solid phase or a mixture of liquid and solid phase and a gaseous phase are obtained,

30 and the gaseous phase is separated.

12. The method according to any one of claims 7 to 11, wherein the reaction in step 1 with a molar ratio of in total dinitrile and diamine to water from 1: 1 to 1:30.

35

13. The method according to any one of claims 7 to 12, wherein in stage 3 the gaseous or liquid phase containing water in an amount of 50 to 1500 ml of water per 1 kg of first liquid or first solid phase or mixture of first liquid and 0 first solid phase is added.

14. The method according to any one of claims 7 to 13, wherein at least one of the gas phases obtained in the respective stages is returned to at least one of the preceding stages. 5

15. The method according to any one of claims 1 to 14, wherein an alpha, omega-alkylenedinitrile with an alkylene radical (-CH ₂ -) of 3 to 11 carbon atoms or an alkylaryldinitrile with 7 to 12 carbon atoms is reacted as dinitrile.

16. The method according to any one of claims 1 to 15, wherein adiponitrile is used as the dinitrile.

17. The method according to any one of claims 1 to 16, wherein an alpha, omega-alkylenediamine with an alkylene radical (-CH ₂ -) of 3 to 14 carbon atoms or an alkylaryldiarr.in with 9 to 14 carbon atoms is used as the diamine ,

18. The method according to any one of claims 1 to 17, wherein hexamethylene diamine is used as the diamine.

19. The method according to any one of claims 1 to 18, wherein the following mixture is used:

from 50 to 99.99% by weight of dinitrile and diamine in total, from 0.01 to 50% by weight of at least one dicarboxylic acid selected from the

Group consisting of aliphatic C ₄ -Cι ₀ -α, ω-

Dicarboxylic acids, aromatic

C ₈ -C ₂ -dicarboxylic acids and

Cs-Ca-cycloalkanedicarboxylic acids, from 0 to less than 50% by weight of an ammonium nitrile and from 0 to 50% by weight of an α, ω-Cs-C ₂ amino acid or the corresponding

Lactams, from 0 to 10% by weight of at least one inorganic acid or salt thereof,

the sum of the individual% by weight data being 100%,

20. The method according to any one of claims 1 to 19, wherein the diamine is used dissolved in water.

21. Polyamide, producible by a process according to one of claims 1 to 20.